Truss end construction



Aug. 29, 1950* A. v. PEDERSEN TRUSS END CONSTRUCTION Filed July 3, 1947.n we L mp m 4 4232b r-ney;

.terially wider than the lower chord. .ltruss designs the materialsemployed .are such Jthat the lower chord need not be as 'wide' or asthick as the upper chord and in order to most advantageously employ thematerial .used it is Patented Aug. 29, 1950 UNITED 'TRUSSENDCONSTRUCTION Axel VrPedersen, Los Angeles; .Calif.

IApplication'July'3; 19 .17; Serial No. 758,757

- zfllaims.

.'This invention relates to improvements -'in truss end "constructions.The conventional wooden truss used in'the construction-ofbuildings'has acurved'upper chordimwhich-compression stresses are'developed and a''horizontal lower chord in'which tension-stresses are developed.Heretofore metal shoes have frequently been employed toformaconnectionbetween the ends of the upper chord and the'ends of the lowerchord. 'These"shoes, 'while satisfactory, have the objection thatthey'are-sometimes'difiicult to fit in transmitting the compressivestresses from the upper chord to the lowerchord so that the lowerchord'may' properly perform its function of resisting spreading-of theends of the upper chord.

In the manufacturingoftrusses'of this type the upper chord is usuallymade up of *laminations and there frequently is a considerableamount ofscrap material available in cutting andposition- .ing the laminations ofthe upper chord so that they have staggered joints.

4 An object of the present invention is to provide an improved truss endconstructionwhich is highly advantageous in that it enables a propertransfer of stresses'from the upper chord to the-lower. chord and whichwill enable the utilization of a substantial portion of lamination scrapthat would otherwise be wasted.

Another object .of the invention .is'to provide a truss end constructionwhich will enablea I'satisfa'ctory 'connectionlto be made between thelcurved upper. chord and the horizontal lower chord even. though theupper chord maybe ma- In. many desirable to have the. lower chord ofsmaller dimensions than the upper chord. Particularly Lis .Qthis. truewhere weight of the entireztruss is'an .impor.tantfactor. The improvedtruss end construction enables .the use of such chords and pro-"accompanyingdrawings'for' an illustrative embodiment of the invention.wherein:

Figure 1 isra view-in side elevation of the end of a. truss embodyingthe present invention;

Figs. land 3 are partialviews in elevation ;.taken substantially uponthlines'l 2--2.-.and 3--3,

respectively, upon Figffin the direc'tiondndicated; and

Fig.4 is a view side elevation of a modi fied or alternate form ofconstruction embodyingtthe present invention.

Referring -to --the '-accompanying drawings wherein similar referencecharacters designate similar parts throughout, -10= indicates wthe endof a curved upper chord of a wooden truss. H indicates-the-end ofthe:horizontal: chord of the truss. Inaccordancewith-common practice thecurved upper chord-i0 is made-uplofi-a seriesi'of wooden laminationsthat are glued together and which collectively .are .bent to.thezzdesired cur-.ve of-the upper chord. .The .lower. chord. l.l;.may;bebut ordinarily is notlaminated. In thezcourse of constructionofi thetnusstherexfrequently .develops a. inumberaof1shortopieces:of.laminations which heretofore have either been wastedioremployedl inaa m'annerdzhat'is notzzparticularly useful. In. accordancecwithathe present. invention these laminations are, utilizedto providethe-con- :nection between the :endrofi ithe iuppenchord til andztheendof thellowerrchordwl i. 1.111 so. doing the laminations. aretrimmed2- along their-iaees so as itoibe.taperedzasindicatedaat 12. Thesetapered laminations cthen. have their abutting faces glued together;so-that thepglue planesor planes oi" adhesionibetween adjacentlaminations .in effect; radiate from a center located at the innersection of the axis ofttheiendofthelower chord lllandthe axismfitheend-.-of the-.=upper chord iii. .'I!he uppermost .laminations indicatedat I3 and which are disposed in planes substantially parallel to. the,end of. the upper-chord l0 needwnot be tapered .and,.preferably..havetheglue planes or. adhesion planestherbtween arranged substantially:parallel-to. the. axis, of-the end of the upper. chord. In. asimilarmanner the-lowermost laminations Mneed not be tapered and may bearranged parallel to the length bf the horizontal chord H Whentheblockof. glue laminations is thus-prepared. itisready for assembly with.theends of the .upper and. lower chords. Anyformnf rconnectionb'etweenthis block and the end of the upper chord that is suitable fortransmitting compressive stresses from the upper chord. to theblobk-maybeemployed and'likewiseany' formof connection suitable fortransmitting tensionstresses between the bottom of'the block of.laminations and the end of the lower chord"! I may be employed. "In thepreferredform oftcon'struction, howeverf-I preferto employ a wood jointof 'the typedis closed in my :copending application Serial No. 516,067,filed .December 29 11943; *nowabandoned,

whereinthe end'of theupper chord-"iflhas oppositely shaped" scarfs I5and lt 'formewthereon, one above the other. The slopes of these scaris 3are preferably less than 1:6 and usually are in the neighborhood of 1:10or 1:12. In a similar manner the upper portion of the triangularlaminated block is equipped with complementary scarfs indicated at I!and I8. The end of the lower chord H is similarly scarfed as indicatedat [9 and 20 and complementary scarfs 2i and 22 are formed on thelaminated block. These opposed mutually engaging scarfed faces on thechords and on the block are glued to each other thus completing theconnection between the upper chord and the lower chord. noted that bythis construction the glue planes or planes of adhesion between thelaminations of the block gradually and progressively change in positionfrom the horizontal, which is parallel to the horizontal bottom chordII, to a position parallel to the end of the upper chord l0. These glueplanes or planes of adhesion are thus most advantageously arranged totransmit the shear developed in the block between the compressive upperchord l9 and the horizontal lower chord II which is under tension.Usually the ability of the adhesive to carry shear stresses is greaterthan that of the wood laminations itself but as u the wood laminationsare relatively thin they are capable of carrying this shear stress underordinary truss design if the thickness of the block is made equal to thethickness of the upper chord. lamination scraps to advantage but, by thearrangement of the glue planes, I may nicely and in a distributed mannertransmit compression from the upper chord to the tensile lower chord H.

In many forms of truss design it is desirable to utilize a thinner lowerchord I I than the upper chord IE and to this end the lower chord II isshown as being considerably thinner than the block of laminations l2 inFig. 3. With this arrangement, one side of the lower chord is disposedfiush with one side of the laminated block and the scarfs cut on thelaminated block to complement the scarfs on the end of thelower chord.At the end of the innermost scarf 29 on the lower chord the block maymerely be shouldered as indicated at 23.

' In Fig. i there is disclosed an alternate form of construction whereinthe lamination scraps have been tapered glued together to form a blockgenerally indicated at 24 wherein the glue planes approximately radiatefrom a center at the intersection of the upper chord as extended withthe lower chord as extended. In this form of construction any type ofconnection may be employed to transmit compressive stresses from theupper chord to the block, but a double scarfed wood joint as abovedescribed has been illustrated. The lower chord 28 has its top surfacepositioned directly against the bottom of the laminated block and glueddirectly thereto. In this form of construction it is not essential touse untapered laminations corresponding to those illustrated t I3 and Mon Fig. 1. The stress developed in the block is transmitted directly tothe lower chord through the glued surfaces at 21 and immediately abovethe lower chord the laminations of the block may start taperingimmediately. While there is a slight departure of the uppermost glueplanes of the block from being exactly parallel with'the end of theupper chord 25, this slight departure is ordinarily not of any greatconsequence. In both It will be In this way I am able to not only useforms of construction as illustrated, the glue planes between thelaminations of the block are approximately parallel to the direction ofshear in their respective locations.

It will be appreciated. from the above described construction that theimproved truss end connection is quite versatile in that it optionallyenables the upper and lower chords to be either of equal thickness or ofunequal thickness. Furthermore, accurate fitting of parts as in the caseof a metal shoe is not required.

In the conventional wooden truss construction the laminations of theupper and lower chords are made from boards wherein the grain runslengthwise thereof and as the laminations l2 and 24 are usually preparedfrom scraps from these boards they will likewise have their grainsrunning lengthwise thereof. The trimming of these scraps or pieces totaper them does not alter or affect their grain arrangement withrelation to the lengths of the laminations. Consequently when thetapered laminations are stacked together the grains of the laminationswill be running lengthwise substantially parallel to the glue planesbetween adjacent laminations.

Various changes may be made in the details of construction withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

I claim:

1. A wooden truss having a horizontal lower chord and a curved upperchord, the ends of the chords being adjacent each other and arranged sothat their axes if projected would intersect each other at an angle, astack of tapered wooden laminations between the chord ends glued to eachother and to the chords, said laminations having their grains runninglengthwise thereof, the tapers of the laminations being substantiallyuniform toward the apex of said angle whereby the glue planes betweenadjacent ymr laminations progressively change from substantiallyhorizontal near the end of the lower chord to an inclined position nearthe upper chord substantially parallel to the end of the upper chord.

2. A wooden truss having a horizontal lower chord and a curved upperchord, the ends of the chords being adjacent each other and arranged sothat their axes if projected would intersect each other at an angle, astack of tapered wooden laminations between the chord ends glued to eachother and to the chords, said laminations having their grains runninglengthwise thereof, the tapers of the laminations being substantiallyuniform toward the apex of said angle whereby the glue planes betweenadjacent laminations progressively change from substantially horizontalnear the end of the lower chord to an inclined position near the upperchord substantially parallel to the end of the upper chord, each chordhaving a scarfed joint with the stack of laminations in the form ofopposed scarfs on each the chord and lamination stack, which extendacross a vertical plane through the stack.

AXEL V. PEDERSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

FOREIGN PATENTS Number Country Date 77,435 Austria Aug. 15, 1918 488,463France Oct. 15, 1918

